Galactosyltransferases are the family of enzymes which transfer galactose from UDP-gal to the non-reducing residues of oligosaccharides of various glycoconjugates as well as to monosaccharides. N-acetylglucosaminide Beta1-4 galactosyltransferase is a specific transferase, secreted in milk as part of lactose synthetase complex which transfers galactose through Beta1-4 linkage to terminal N-acetylglucosamine residues in glycoproteins. Alpha-Lactalbumin modifies the activity of this galactosyltransferase in such a way that it inhibits the transfer of galactose from UDP-galactose to N-acetylglucosamine either free or linked as a terminal sugar of a glyco-protein, but facilitates the transfer to glucose or myo-inositol. To understand the modulation of galactosyltransferase activity essential for generating specific cell surface antigenic determinants, we have first isolated and characterized cDNA clones corresponding to Alpha-lactalbumin. Protein sequence, isolation and the sequence of the cDNA clones corresponding to the galactosyltransferases, which is essential in understanding the molecular mechanism of the modulation of the transferases and the control of their gene expression, is being investigated.